Agenda item

Agenda item


To consider a report by the Flood Risk Engineer, Wayne Hope, into the investigation of the flooding on 9th February 2020 (copy attached).




The Lead Member for Waste, Transport and the Environment, Councillor Brian Jones, introduced the 9 February 2020 Flood Event - Section 19 Flood Investigation Report.


On the 9th of February 2020, extensive flooding occurred across Denbighshire as a result of Storm Ciara. Council officers, as well as officers from Natural Resources Wales (NRW) and Dŵr Cymru Welsh Water, had since carried out investigations into the flooding to understand the reason why the flooding occurred, the likelihood of it happening again and to assess whether measures could be put in place to reduce flooding in future.


Keith Ivens of NRW commenced with the queries raised regarding St. Asaph.  He confirmed that the event in February 2020 had been an extreme event.  The new defences were constructed, built and designed on a 1 in 100 year standard of protection including allowance for climate change.  What had been seen in the event analysis in Appendix B was a hydrological analysis of occurrences due to Storm Ciara.


Storm Ciara was estimated to be a 1 in 250 / 1 in 300 year event at peak flow. Immediately after the event it had been queried why there had been overtopping in one particular location.  Extensive discussions had taken place with the designers, and an extensive post event modelling carried out with the designers to understand what happened in that location.  It had been resolved with the designers which had led to the works which were currently being carried out in St. Asaph.  The community of St. Asaph had very good protection and 370 properties had been protected which would have been flooded otherwise. 


Failure of water level recorder in St. Asaph under the A55.  The type of equipment installed at that location was a pressure transducer which was set with an upper and lower limit, but it had exceeded the upper limit. The pressure transducer was still in place but an additional downward facing ultrasonic level sensor was now situated on the new Spring Gardens Bridge which allowed NRW to monitor water levels and that fed into the flood forecasting model for the River Elwy


Protection of rural communities - Wigfair and Lower Denbigh Road area had been looked at as part of the St. Asaph scheme to ascertain if some of the properties along that area could be included within the scheme.   At that point it had been decided it would not be possible to include the properties, as it would make the scheme uneconomical and therefore, could not take that forward.  A number of the properties  were offered and provided with property level protection. 


There was a question mark around reviewing flood map outlines around those areas.  Over the last 12/18 months NRW had been working with Welsh Government to review, update and replace the old flood maps that were available and new flood maps called Flood Risk Assessment Wales were released earlier this year which looked at all the flooding from surface water, river flooding, none main river flooding all in one location.


Property level protection was in the NRW 1-5 year recommendation.   There had been a property level protection pilot running in Llanfair TH.  Results of the pilot would be assessed and would then look at other small and rural communities which would not benefit from a larger scheme and also look at other alternatives with property level protection being one of those. 


Inevitably it was always difficult in smaller more rural communities to achieve the cost benefits to address and design a larger scheme which was why NRW assessed alternative options.  NRW looked at trying to achieve the greatest level of protection for the greatest number of properties as possible.


The question raised regarding a valve in St. Asaph being opened – it was not actually a valve, it was a flap which had lifted and held in place so it was a gravity fed flap which required the pressure of water behind it to push it open.  The inspection regime had been increased around that to ensure that during and after events it was working as it should be.


Councillor Peter Scott had sent an enquiry in to NRW regarding Glan Llyn Farm.  Officers from NRW had visited Glan Llyn Farm where discussions had taken place regarding their plans which were very positive but, unfortunately, currently the window for NFM (Natural Flood Management) funding was closed so no grant funding would be available at the current time.   A full response would be provided to Councillor Peter Scott.


Councillor Arwel Roberts had raised the risk in Rhuddlan.  The Risk in Rhuddlan formed part of the Dee and Clwyd Strategy and there was an increasing risk due to climate change.  In Rhuddlan there was a dual risk of tidal and fluvial flooding.  A review had been carried out approximately two years ago but NRW were satisfied that currently everything from a tidal perspective was as it should be.  NRW recognised there was an increase in storms and increase in fluvial flows and that piece of work would have been considered as part of the additional work in St. Asaph.  A full response would be provided to Councillor Arwel Roberts.


Regarding insurance, it had been recognised that those properties affected by flooding did have either increased premiums or larger amount they have to pay out before the insurance would provide additional funding.  NRW advised that if residents were living in a flood risk area and had been affected by flooding then they should have discussions with the insurance companies but also contact the National Flood Forum who were a National Charity.  The National Flood Forum would be able to provide independent advice but there was also the Flood Re Scheme which could help to provide advice for people having difficulties regarding insurance.  It was up to an individual insurer if they chose to insure a property and they would consider the risk associated with it.  The insurers would not necessarily look at NRW flood maps and would make the decision themselves.  NRW were not involved with how insurers determined their premiums. 


Issues in Llanynys was within the medium term recommendation list which would be addressed between 1 – 5 years.   It had been very challenging as flooding had taken place on 9 February 2020 and then the country had been put into lockdown in March 2020.  Many people were working from home, home schooling and it had to be considered it was not an excuse but had to consider all the recommendations and the work which had been achieved.  It continued to be a challenge and NRW were also seeing challenges around contractors, suppliers providing information and getting information from consultants etc., who were also in lockdown.  It had also been very difficult getting surveyors out on site.  NRW were following Welsh Government guidelines which, obviously had a lot of restrictions, how they were operating and as well as protecting staff needed to protect the community also.  More work needed to be carried out in Llanynys as that issue had not been addressed and it was on the medium term list but a full response would be provided to Councillor Merfyn Parry.


Flood Risk Activity Permits were in place for any works on a main river or within seven metres of the river bank.  Any structure that needed to go over or under the main river required a Flood Risk Activity Permit and assess what impact it had on flood risk elsewhere but also in terms of the environmental impact eg: fisheries, biodiversity, ecology etc., of the river system.   There was a process for a permit application and if anyone worked on main rivers they would need to apply to NRW for that permit.  If they were working on none main river then that permit would be issued through the Local Authority.  A legal process needed to be followed to obtain a permit.   


Flood Risk across the county was a concern for both the Local Authority and NRW but the National Flood Management Project looked at the catchment (Clwyd catchment included the Rivers Clwyd, Elwy and Dee).   NRW were looking at ways flow could be held back in the catchment which could have some benefit to the communities downstream.  NRW were pro-active but had to bear in mind with the impact of climate change, things seemed to be getting worse not better, so there was only so much which could be done to counteract nature.


Keith Ivens confirmed NRW had programmes, medium and long term plans which were 5-10 years ahead looking at a number of defences, existing schemes and looking at the current standard of protection.  With the latest climate change projections, NRW were reviewing those to ascertain if they were still fit for purpose for now and in the future.  Where any improvement works or upgrades were taking place, the impact of climate change would be considered as part of that, and the predicted increases in flows and levels would also be factored into the work. 


The Chief Executive confirmed the responsibility to flooding was an emergency planning issue.  A report would be presented to all Members once amendments were made to existing practices.  The Chief Executive would brief the Lead Member for Emergency Planning, Councillor Mark Young, imminently whereupon a decision would be made how to take that forward in terms of engaging with the wider membership.


The Local Authority were in the process of constructing another coastal defence scheme to address the risk of flooding in future in Prestatyn and Rhyl.


Keith Ivens was thanked for attending and responding to questions put forward by Members.


Proposed by Councillor Brian Jones, seconded by Councillor Peter Scott to accept the report.


A vote took place and it was unanimously agreed to accept the report.



(i)            Members consider the flood investigation report and provide feedback and comments.

(ii)          The Council seeks assurance from Natural Resources Wales that the recommendations identified in Natural Resources Wales’ flood investigation reports will be carried out


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